Temporal and spatial varieties of future wave climate under the scenario of climate change

Examining the wave climate under climate change scenarios requires a concurrent analysis of both historical and predicted future wave data. This involves using historical wave data to understand seasonal fluctuations and long-term trends, while also utilizing future wave data to predict waves under diverse climate change scenarios. This information is pivotal for evaluating forthcoming risks and formulating strategies for climate change adaptation. This study employs historical wind field data, including ERA5 reanalysis data and CWB/WRF analysis field data, as well as wind field data from the CMIP6 dataset under the SSP5-8.5 extremely high emission scenario. These data are used to drive the WAVEWATCH III wave model for simulating waves. This study initially compared the simulated wave data from the WAVEWATCH III wave model with one year of observed wave data from met-ocean buoys. The results confirmed the high credibility of the simulated waves. Subsequently, extensive data simulations are conducted, encompassing historical wave data (1975-2022) and projected wave data for the future (2025-2100).

This study delves into the long-term temporal variations in wave height in Taiwanese waters and the differential regional trends in spatial changes. Regarding temporal changes, the wave heights are averaged year by year, and then linear regression is performed in units of years. The slope of the regression equation indicates the long-term linear trend of wave height in Taiwanese waters over the years, revealing an increasing trend from the past to the future. Regarding spatial changes, the average wave height at each grid point is calculated, and linear regression is applied to determine the long-term trends in wave height at each grid point from the past to the future. The findings unveil a positive growth trend in Taiwanese waters. Furthermore, Taiwanese watersexperience distinct weather patterns in each season, such as the influence of the northeasterly monsoon in winter and typhoons or southwestern winds in summer. This study further explores the differences and variations of wave during spring (March to May), summer (June to August), autumn (September to November), and winter (December to February of the following year). The analysis results indicate negative growth trends in spring and summer, and positive growth trends are observed in autumn and winter, indicating a noticeable increase in wave height in Taiwanese waters during autumn and winter under the influence of climate change.